This invention relates generally to cellular cushions, and more particularly, to cellular cushions that include support material.
Individuals confined to wheelchairs may run the risk of tissue breakdown and the development of pressure sores, all of which may be extremely dangerous and difficult to cure. More specifically, because such individuals may primarily be in a seated position for extended periods of time, their weight may be concentrated in the bonier portions of the individual's buttocks. Over time, blood flow to such areas may decrease, causing tissue to break down.
To reduce the weight concentration of such individuals, at least some known wheelchairs use cellular cushions that facilitate distributing the individual's weight over a larger area and across the individual's buttocks, and that decreasing their weight concentration in smaller areas. At least some known cellular cushions include a plurality of hollow fluid-filled cells that project upwardly from a common base. More specifically, because the air-filled cells are coupled in flow communication through the base, the air within such cells is at the same pressure throughout the plurality of cells, and as such, each cell exerts the same pressure against an individual's buttocks.
Because all of the cells are at the same pressure across the base, the plurality of cells may provide less stability to the seated individual in comparison to a substantially planar seating surface. To increase the stability of the user, at least some cushions enable the user to control their immersion depth into the cushion and/or their relative position on the cushion by varying the pressure of the air in the cells or in a zone of cells. By varying the pressure in the cells or in a zone of cells, the user may be able to increase their stability on the cellular cushion and/or selectively change their posture on the cushion. Although the pressure in the cells may be varied, the general contour of the cushion remains the same.
To provide additional support and stability to users, at least some cellular cushions are fabricated with cells that are formed with various heights or cells that include a contoured outer surface. The cells in such cushions are oriented in an arrangement that defines a contoured seating surface for the user. Moreover, the seating surface remains contoured as the immersion depth is varied by the user. However, depending on the user, such as those users having deformities (skeletal or otherwise) or those that lack muscular strength in their pelvis and/or thigh regions, portions of the user may bottom out (i.e., fully compress the cells) if the pressure in the cells is decreased in cellular cushions. Moreover, cellular cushions including cells of varying heights and/or cells having contoured outer surfaces is generally more difficult and costly to manufacture.